And since i'm not familiar with blk file structure, do you think there's possibility of false positive?
Of course. The only thing that happens is that it tries to find "1976a914<20_bytes>88ac" in raw bytes. That means, if you put such value on a stack, it will be reported, even if it is not the real address. The same will happen if you wrap it inside OP_RETURN.
You can try running it on regtest, for example with a transaction similar to this one:
decoderawtransaction 02000000000101af811dc710445dc189131791c37757783ebd83ff1f73140b5322db9875c585ee0000000000fdffffff0200f2052a0100000005827701198700000000000000001b6a1976a914108f77aa04c12e58c6c9213faf20f16668c74aed88ac02473044022038aa002c72932ce9081943804ad4d61f31affea22a5f6c840da8c5cb7296fe920220316ad5fc8130cc662e3d920ff8118258314ad308ee04f7e80715dfb4683a68280121038469881ff2b56c969b3abc74ed3863cc6836f3cabd107fbe20aeafb61a5a471700000000
{
"txid": "b60ccfab381f272e6ff8adf761ea8ecf26955527e49423a146d1dd4426f634d6",
"hash": "d683804ede8342c1658a8ddb502026d09fb8ff3659583f3d5edee60c351385f5",
"version": 2,
"size": 210,
"vsize": 129,
"weight": 513,
"locktime": 0,
"vin": [
{
"txid": "ee85c57598db22530b14731fff83bd3e785777c391171389c15d4410c71d81af",
"vout": 0,
"scriptSig": {
"asm": "",
"hex": ""
},
"txinwitness": [
"3044022038aa002c72932ce9081943804ad4d61f31affea22a5f6c840da8c5cb7296fe920220316ad5fc8130cc662e3d920ff8118258314ad308ee04f7e80715dfb4683a682801",
"038469881ff2b56c969b3abc74ed3863cc6836f3cabd107fbe20aeafb61a5a4717"
],
"sequence": 4294967293
}
],
"vout": [
{
"value": 50.00000000,
"n": 0,
"scriptPubKey": {
"asm": "OP_SIZE OP_NIP 25 OP_EQUAL",
"desc": "raw(8277011987)#gm6fdvfy",
"hex": "8277011987",
"type": "nonstandard"
}
},
{
"value": 0.00000000,
"n": 1,
"scriptPubKey": {
"asm": "OP_RETURN 76a914108f77aa04c12e58c6c9213faf20f16668c74aed88ac",
"desc": "raw(6a1976a914108f77aa04c12e58c6c9213faf20f16668c74aed88ac)#kgcumtgs",
"hex": "6a1976a914108f77aa04c12e58c6c9213faf20f16668c74aed88ac",
"type": "nulldata"
}
}
]
}
Or maybe that one:
decoderawtransaction 0200000001d634f62644ddd146a12394e427559526cf8eea61f7adf86f2e271f38abcf0cb6000000001a1976a914108f77aa04c12e58c6c9213faf20f16668c74aed88acfdffffff0100f2052a01000000160014108f77aa04c12e58c6c9213faf20f16668c74aed00000000
{
"txid": "51a53ab132edf078112d98c48a4d3df64061f7689f362a75b5a25712ebc25777",
"hash": "51a53ab132edf078112d98c48a4d3df64061f7689f362a75b5a25712ebc25777",
"version": 2,
"size": 108,
"vsize": 108,
"weight": 432,
"locktime": 0,
"vin": [
{
"txid": "b60ccfab381f272e6ff8adf761ea8ecf26955527e49423a146d1dd4426f634d6",
"vout": 0,
"scriptSig": {
"asm": "76a914108f77aa04c12e58c6c9213faf20f16668c74aed88ac",
"hex": "1976a914108f77aa04c12e58c6c9213faf20f16668c74aed88ac"
},
"sequence": 4294967293
}
],
"vout": [
{
"value": 50.00000000,
"n": 0,
"scriptPubKey": {
"asm": "0 108f77aa04c12e58c6c9213faf20f16668c74aed",
"desc": "addr(bcrt1qzz8h02sycyh933kfyyl67g83ve5vwjhd82v7z9)#0w4jaj80",
"hex": "0014108f77aa04c12e58c6c9213faf20f16668c74aed",
"address": "bcrt1qzz8h02sycyh933kfyyl67g83ve5vwjhd82v7z9",
"type": "witness_v0_keyhash"
}
}
]
}